/Engine/Source/Runtime/GeometryCore/Public/Polygon2.h
Get the previous and next vertex positions for a given vertex of the Polygon
void NeighbourPoints ( int VertexIdx, [TVector2](API\Runtime\Core\Math\TVector2)< T > & OutPrevNbr, [TVector2](API\Runtime\Core\Math\TVector2)< T > & OutNextNbr ) const